584 
Chemistry. — “On the relation between the sulphur modifications.” 
By Dr. H. L. pr Leeuw. (Communicated by Prof. A. F. Horr.mMman). 
(Communicated in the meeting of September 28, 1912). 
Prof. Sirs has authorised me to criticise a recently published 
report of a lecture by Krurr delivered before the Deutsche Bunsen 
Gesellschaft (Z. f. Elektr. Chem. 1912, 10, 581) and to make use for 
this of the experimental data obtained during a research conducted 
by me as private assistent. Before proceeding to this it seems to 
me desirable to mention very briefly some points in historical order. 
Smita and his coadjutors were the first to assume dynamic isomery 
with sulphur. They determined the course of the equilibrium line 
S,—S, and also the solidification line of the monoclinic sulphur. 
Kruyt, in addition, determined the initial melting points of rhombic 
sulphur which, at different temperatures, had got into equilibrium 
with S,, the melting point line of Surru being used as the method 
of analysis. Moreover, he concluded to the existence of a metastable 
region of demiscibility contrary to SmitH and his co-workers who 
rejected this. 
By Prof. Smits it was pointed out already in 1910 that the results of the 
sulphur investigation contain data which support his theory of allo 
tropy. Kruyt, for instance, had stated that when starting with rhombic 
sulphur, which has placed itself in equilibrium at 90° and then 
determining the melting point of the sulphur in this condition, according 
to Socn’s method, 110°.9 was found whereas, in the same method 
of working, & melting point of 111°.4 was observed when the S had 
come into equilibrium at 65°. From this result it, of course, follows 
that we are dealing here with an inner equilibrium in the solid 
state, therefore with mixed crystals, and that the line for the 
inner equilibrium in the solid condition proceeds on increasing the 
temperature, to a greater S, content, as in the liquid. Prof. Sirs 
therefore changed the 7, x-figure (fig. 1) into that indicated in fig. 2. 
Afterwards, A. SmitH and Carson (Z. f. phys. Chem. 1911, 77, 
661) have determined the solidification line of Sr, also making use 
of the lines determined previously. This line differs a little with 
the curve of Kruyr. Moreover, they also found a third melting point 
line, tbat of the “soufre nacre’. In the same time Kruyr (Chem. 
Weekblad 1911, 647) announced that all the values of the transition 
temperature (7’—), with varying quantities of S, are situated lower 
than Reicuer’s value (95°.6) and also that the dimensions of the 
mixed erystal-region are not such that the influence thereof on his 
calculations exceeds the experimental errors. 
